Hole-forming attachment for powder press

ABSTRACT

AN ISOSTATIC POWDER PRESS FOR FORMING TOILET TANKS OR OTHER ARTICLES HAVING HOLES FORMED THERETHROUGH. ONE OF THE DIE MECHANISMS IN THE PRESS IS PROVIDED WITH AN ANNULAR SLEEVE WHICH MOVES INTO THE POWER DURING THE COMPACTION STROKE TO ENTRAP THE POWDER AND FORM A HOLE   THROUGH THE FINISHED ARTICLE. THE HOLE IS FORMED WITHOUT STRESSING THE COMPACTED ARTICLE, THUS MINIMIZING THE TENDENCY FOR CRACKS TO OCCUR ADJACENT THE HOLE DURING THE GLAZING AND FIRING PERIODS.

Nov. 9, 1971 W. ca. ANDERSON E'TAL Bfiflfl? HOLE-FORMING ATTACHMENT FORPOWDER PRESS Filed. Sept. 22, 1969 Flt-3.1

United States Patent 3,618,179 HOLE-FORMING AT'lllAClglMENT FOR POWDERRE S Warren Gregory Anderson, New Orleans, 11.21., and Curtis WayneOgren, Louisville, Ky., assignors to American Standard lino, New York,N.Y.

Filed Sept. 22, 1969, Ser. No. 859,846 Int. Cl. B28h 7/06, 7/18, 7/32US. Cl. 25-27 Claims ABSTRACT OF THE DISCLOSURE THE DRAWINGS FIG. 1 is asectional view taken through a press constructed according to theinvention. FIGS. 2, 3, and 4 are fragmentary sectional views of otherpress constructions utilizing the invention.

FIG. 1 in greater detail There is shown in FIG. 1 an isostatic powderpress comprising first and second separable die mechanisms 10 and 12advanceable together to define a ceramic powder powder cavity 14, andretractable from each other to expose the formed article; in this casethe article is a toilet tank having a bottom wall 16 and a peripheralside wall 18. The tank article is shown being formed in an upside downposition, although it could be formed rightside up if desired. The diemechanisms separate on a parting line 15.

Die mechanism 10 comprises a rigid plastic or metallic core section 20having a peripheral flange 22 which mates with an annular clamping plate24, said plate 24 serving to anchor the peripheral flange 26 of aresilient deformable rubber membrane 28. The outer or upper surface 30of the membrane forms a movable die surface for compressing powder withcavity 14. To effect outward and upward movement of membrane 30 there isprovided in core 20 a fluid passage 32 leading to one or more fluidchannels 34 in the core surface. Admission of pressure fluid into fluidpassage 32 causes the membrane 30 to deform upwardly and outwardly, tothus compact the powder from the illustrated thickness to the thicknessgenerally denoted by arrows 36. Line 38 denotes the interior surface ofthe final article after the compaction stroke.

Die mechanism 12 comprises a rigid mold member 40 having a female moldcavity surface 42 and an opening 44 which is normally closed by a covermember 46; member 46 forms part of the die mechanism during thecompaction process. When cover member 46 is removed from member 40powder can be introduced through opening 44, as by blowing or pouringprocedures. Thereafter the die mechanisms 10 and 12 may be held togetherby force means 48 (clamps, vises, presses, etc.) and pressure fluidapplied through passage 32 to deform the membrane 28 upward and outward,thus compacting the powder to the final thickness denoted by numeral 36.

Cover 46 carries one or more sleeves 50 thereon. During the compactionstroke of the membrane the lower peripheral end edge 52 of the sleevecauses powder to be 3,fil8,l79 Patented Nov. 9, i971 entrapped withinthe sleeve. At the end of the compaction stroke the membranesubstantially engages the peripheral edge 52 of the sleeve, and theentrapped powder is substantially disconnected from the compactedarticle. Upon reverse movement of the membrane and removal of cover 46from mold member 40,. the entrapped powder is removed with sleeve 50,leaving a hole through the article. The shape of the hole (round,square, slot-like, etc.) will be determined by the shape of sleeve 50.The compacted article is dried, glazed and fired, as under conventionalpractice, to form a rigid useful ceramic article.

Prior to this invention holes were formed by means of cookie cutterimplements pressed into the green uncured article. After glazing andfiring, cracks sometimes developed because the hole-forming operationwas performed after the article had been compacted. It is believed thatduring the hole-punching operation the material adjacent the hole wasdeformed or stressed to a greater extent than other portions of thearticle so that the higher stressed areas tended to expand or relievethemselves during the firing period, resulting in stress riser cracks.

By forming the holes during the compaction process the stress risercracks are eliminated. It is believed that this is because the sleeve 50slices into the powder material as it is being compacted so that thepowders can shift before they have become substantially welded together.Thus, the shifting of the powders occurs while there is still room orspace for the powders to avoid one another; at firing there are fewerstresses which have to be relieved.

FIG. 1 illustrates one form which the sleeve 50 can take in the practiceof the invention. Another form is shown in FIG. 2. As there shown, thesleeve is formed with an upper end wall 54 having airjet openings 56therethrough. The purpose in these jet openings is to permit ejection ofthe entrapped powder after completion of the compaction operation. Thus,after cover 46 has been removed from opening 44 compressed air can beintroduced through the opening 58 to produce jets of air against theinterior back face of the powder disk. The airjets effectively dischargethe powder disk and clean the sleeve 50 for the next cycle.

FIG. 3 illustrates another form which the sleeve can take. As shown inFIG. 3, the sleeve 50 is slidably retained within an opening in covermember 46 and is biased toward the membrane 28 by means of a compressionspring 60. A plate 62 is suitably affixed to the cover 46 to retain thespring 60 in place.

The FIG. 3 sleeve 50 protrudes from the surface of die mechanism 12 thefull initial thickness of the powder space. Thus member 28 engages thesleeve from the beginning of the compaction stroke until the end of thestroke. As the compaction movement takes place the sleeve 50 movesupwardly, and the spring 60 collapses accordingly. Spring 60 is ofcourse a comparatively light spring, sufficient only to keep the sleeve50* engaged with member 28 but ineffective to deter the membrane fromits designated movement. At conclusion of the compaction operation a jetof air can be introduced through opening 64 to aid in removal of thepowder entrapped within sleeve 50.

FIG. 4 illustrates an arrangement wherein sleeve 50 is carried by themembrane 28 rather than cover 46. During the compaction stroke thesleeve slices through the powder and entraps some of the powder to thusform the hole in the finished article. A depression 66 may be preformedin cover 46 to accept some of the entrapped powder.

We claim:

1. In an isostatic powder press comprising first and second separabledie mechanism advanceable together to define a ceramic cavity forunfired ceramic powder, and retractible from each other to expose theformed uncured article; said first die mechanism including a core, adeformable membrane carried by and lying against said core, and meansfor applying fluid pressure to the interior space between the core andmembrane, whereby to cause said membrane to transmit a compacting forceonto the powder in the cavity: the improvement comprising a sleevehaving a lower peripheral end edge, said sleeve being carried by eitherthe membrane or the second die mechanism, whereby said peripheral endedge of said sleeve directs powder into and entraps powder within thesleeve as the membrane undergoes its powder-compacting movement; saidsleeve being of sufiicient length as to be engaged with the membrane andthe second die mechanism at the end of the compaction stroke, wherebysaid entrapped powder is non-compacted and is substantially disconnectedfrom the compacted article to define a hole through the wall of theuncured article.

2. The press of claim 1 wherein the sleeve is carried on the second diemechanism.

3. The press of claim 1 wherein the second die mechanism is providedwith airjet openings within the space circumscribed by the sleeve,whereby jets of air can act to dislodge compacted powder from within thesleeve.

4. The press of claim 2 wherein the sleeve is slidably mounted withinthe second die mechanism for movement in the direction of its axis; thecombination further comprising spring means biasing the sleeve towardthe membrane, whereby compacting movement of the membrane causes saidmembrane to contact the sleeve before completion of the compactingstroke, and final movement of the membrane causes the sleeve to slideinto the second die mechanism.

5. The press of claim 1 wherein the sleeve is carried by the second diemechanism, said sleeve having an axial protrusion from the second diemechanism equal to the final thickness of the compacted article, wherebythe membrane substantially meets the sleeve as it finishes itscompaction stroke.

References Cited UNITED STATES PATENTS 720,718 2/ 1903 Moddock et a12527 1,120,291 12/1914 Davis 2527 1,677,391 7/1928 Kelso 25--281,689,533 10/1928 Parker 249--113 X 2,865,079 12/1958 Marchioli et al25128 3,133,978 5/1964 Bartley et al.

18-Rubber mold Dig.

ROBERT L. SPICER, 111., Primary Examiner US. Cl. X.R.

25 -129; 249 113, 149; 18Dig. 44

